#canvas {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    margin: 0;
    overflow: hidden;
    background: hsla(0, 5%, 5%, 1);
    background-repeat: no-repeat;
    background-attachment: fixed;
    background-image: linear-gradient(to right top, hsla(0, 5%, 15%, 0.5), hsla(0, 5%, 5%, 1));
    background-image: -moz-linear-gradient(to right top, hsla(0, 5%, 15%, 0.5), hsla(0, 5%, 5%, 1));
}